SYRACUSE, N.Y. -- The Common Council voted unanimously Monday to approve spending $2.5 million next year for private security at Hancock Airport, ending years of costly police overtime.

The council’s approval enables the Syracuse Regional Airport Authority to negotiate a three-year contract with G4S Secure Solutions, of Jupiter, Fla., the company selected to provide security after a request for proposals.

Airport officials hope to have the contract signed by April and to have G4S take over security by June 1.

But the union representing police officers plans to fight the move. Jeff Piedmonte, president of the Syracuse Police Benevolent Association, said he plans to file improper practices charges against the city with the state Public Employee Relations Board.

Piedmonte said the union’s complaint, which will be filed within a week or so, will accuse the city of negotiating in bad faith and of failing to negotiate changes in airport security as part of the police contract.

G4S is expected to hire off-duty police officers for some of the part-time airport positions. Piedmonte said the city could have worked out a cheaper deal by negotiating directly with the union.

The airport authority estimates the contract with G4S will save at least $1.5 million a year compared with the current practice of paying overtime.